I was with my Year 7s, and all of a sudden, there was a loud scream. Bang in the middle of the floor was a spider. We’re talking big, hairy monster, probably fed on genetically modified tomatoes, waving its tentacles at us, obviously excited by our lesson on apostrophes.

The class was paralysed. We couldn’t carry on until the beast had been vanquished. Thirty-two pairs of eyes looked at it. Then 32 pairs of eyes looked at me. Damn. In a flash I realised why blokes were invented. Step by step, terrified, I took my copy of the MEG poetry anthology, coaxed the beast on, and put it out of the window. It was the first time Year 7 realised poetry could actually be useful.

This episode shook me up. Not because of the spider, but because the second those kids turned to me, I realised I had to deal with the situation. I was the adult. This strange, grown-up-type feeling has been afflicting me a lot recently, especially since I began teaching and got a life of my own. I am now an official receiver of wages and payer of council tax, and can empty the filter of my washing machine. Scary. I’m usually the one who does the relying, not the other way round.

Sometimes I don’t feel old enough to be doing this job. “When am I going to feel happy again, Miss?” asked a member of my form, WAR 10, who was feeling down. “Why does everything seem to be going wrong?” I tried to be encouraging, but really I wanted to cry with him.

I don’t have all the answers. I’m only 10 years older than my form, and I sometimes wonder what the hell I’ve done with that extra decade. I don’t seem to have filled it up with anything that can translate into helpful words of wisdom. Being responsible for other people’s lives makes me painfully aware of the silences in my own. I sometimes want to stop discussing other people, and take a meeting about me. Agenda: Gemma. Topics for discussion: Gemma. Any Other Business: Gemma. Sounds good.

Feeling like the oldest 24-year-old in the world is all getting a bit much. So after school, I ignored my pile of marking and decided to go shopping. My entire wardrobe is made up of Laura Ashley, and my friends think I look too much like a teacher. I need to stop being Ms Warren for a while. I marched into the nearest shop. “I want to look like a complete tart, please,” I told the assistant. Who turned out to be a member of Year 13. “I can find you something if you want, Miss,” she said doubtfully, “but it just isn’t you.” How does she know what “you” is? She seems a lot more sure that I am.

I go out to talk to my plants. Gardening is my latest hobby, much to the disgust of my friends. But I love my plants simply because they can’t talk back. They don’t demand attention or need to be marked.

I seem to be plagued with insecurities at the moment, not at all like the teacher I feel I should be. I worry that there isn’t enough inside me to give to all the people who seem to be taking. I worry where my raving, 20-something social life is disappearing to. I worry about greenfly attacking my geraniums. I think I’m having a dark night of the soul. Either that or a bad case of PMT.

In both cases, there’s only one thing to do, however old you are. Be nice to yourself - they don’t teach you that enough on your PGCE. My meeting on Gemma is officially opened, and I’m the major delegation. I feel a trip to the garden centre coming on.

Gemma Warren teaches at the Latymer School, Edmonton, north London